Ice-boat.



W. M. STANBROUGH.

ICE BOAT.

APPLICATION FILED DEG.17, 1910.

Patented Oct. 17, 1911.

7 SHEETS-83KB! 1.

I I I 5513/6; 61k

wilyooeo W. M. STANBRUUGH.

, ICE BOAT.

APPLICATION FILED DEC. 17, 1910.

Patented Oct. 17, 1911.

7 SHEBTSSKEET 2.

7 BHEETS-BHEET 3.

Patented Oct. 17, 1911;

ICE BOAT.

"Q r l mm w W. M. STANBRGIUGH.

APPLICATION FILED DEO.17, 1910. 1,006,310.

- ad M2? fiwfl W. M. STANBROUGH.

ICE BOAT.

'APPLIOATION FILED 1720.17. 1910.

Patnted 0ct.17,1911.'

LQOQBIUD 7 SHEETSSHEET 4.

W. M. STANBROUGH.

1013 BOAT. APPLICATION IILED DEC 17, 1910 Lfi gifl Patented 00t.17,1911.

7 SHEETS-SHEET 5.

W. M. STANBROUGH.

ICE BOAT.

APPLICATION FILED DEO.17,1910.

Patented 0011121911.

7 SHEETSSHBET 6.

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W. M. STANBROUGH.

ICE BOAT.

APPLICATION FILED D2017, 1910.

Patented Oct. 17, 1911.

7 SHEBTSSHEET 7.

a wlfoi Est- 223M?- ,f i To all whonifit may concern.

Be it known that l, VILLIA'M M. STAN- nuorfcn, citizen of'the United States, residing a ewhurgh, in the count-yof Orange and Stzu'e of New York, have invented a new and useful Ice-Boat, of which the following s a specification. i

My ivention relates to an improvement *in'sa propelled ice-boats in-which a member attached to the back-bone or heel of ,thc ice-boat and to the rudder-runner.thercof whereby the lines of supportof the-iceboa't may be shifted from an isosceles triz ingle to a sca-lene triangle, andthe objects of my invention are: (1') to. provide an iceboat of greater stability under Wind pressure and of greater sail carrying ability than the: ordinary type of ice-boat, .(2) an ice-boat of smaller proportions and weight than one of the usual :type, but ca-- pable of carrying the sail area of the larger.

boat with equal or greater speed and greater l /safety and pleasure of operation, '(3) an" ice-lioat in which the centers of gravity may be shifted to windward or leeward of the hack-bone or heel at the will of the operator, (i) an ice-boat in which the centerof gravity of load is utilized asl iallast to a greaterrxtent than in a boat of the usual type, (5) an ce-boat in which the centers of gravity of boat and of boat and load are brought together or approximate so that the boat will turn in a small radius, (6) an ice-boat in which the centers of gravity are so placed that in changing the course in rounding a lee stake the momentum absorbed as thrust by the lee runner instead of becoming-drag on the rudder-runner, usual type of boat, (7), an icel-boat in which the centers of gravity fall together so constructed that the weight of the load gives I stability enough that inertia is overcome in 'a forward direction before the boat lifts (windward runner) froin' the ice, an iceboat in which the lee or forward portion of the sail has a tendency to carry the forward end of the back-bone or keel to leeward and the rear end thereof to windward,while the weather or after portion of the sail, them-ainsheet thereof being fastened to a hinged or movable portion of the rear end of the back bone or keel. tends to hold the rear end of the baclebonc orltccl to leeward, thus causing the (enters of gravity of boatand load to more to windward of the line of stress, (9) an ice-boat in which the cockpit con sra'rns v I, V

,l- WILLIAM 1VL 'STANBROUGH, l

Specification of Letters Patent.

Application filed December 17, 1910. Serial No. 597,873.

in" the arana orricn.

OF NEWIB'ULRGH, NEW YORK.

j meson.

Patented Oct. 1'7, 1911.

having a member for shifting the lines of, support of the ice-boatprovlded at its fore end with a ballast weight, (11) an ice-boat 111 which the centers of gravity can be shifted to windward or leeward of the line of the mast and rudder-runner, (12) an 1ceboat in which the centers of gravity of boat and load automatically shift to windward of the line of the mast and rudder-runner,

(13) an ice-boat in which when the windward runner is raised from the ice by wind pressure, the center of gravity proceeds to windward of the line of the mastand rudder support, I attain these objects by the de-' vice illustrated in the accoinpanyii'ig drawings in which l igure l, is a. plan view of my ice-boat, partly in section. Fig. 2, is an'enlarged longitudinal section on the line 2-2 of Fig. 1. Fig. 3, is a diagrammatic plan view of Fig. 2, with parts removed. i, is an enlarged detail section of the carriage-for operating the shifter, in neutral position. Fig. 5, is a cross section of .liig. at. Fig. 6, is a sectional plan View on the line (3(3 of Fig. 5. Big. 7, is a diagrammatic plan view of my ice-boat. Fig. 8, is a diagrammatic plan view of an ice-boat of-the-nsual type. Fig. 9, is a plan view of a niodificationof my ice-boat. Fig. 10, is a side elevation of another modification of my -ice-l: oat. Fig. 11, is atop plan view of Fig. 10. Fig. 12, 1s a rear elevation of the shifter, rudderrunners and their connections of the modification of my ice-boat shown in Figs. 10 and 11. Fig. 13, is a plan View of Fig. 12. .Fig. 14, is a. top plan View of another inodilication 'of my ice-boat.

Similar numerals refer to similar parts tln-oughoutthe several views.

My ice-boat comprises a back-bone, 1 5, a runner plank, 16, runners, 17, a tiller post, 18, a shifting member, 19, a rurider-runner,

20, and cock-pit or box for the crew, 21.

The hack-bone, 1?. is of the form com- .monly used in," ice-boats with the usual means for stepping the mast and attaching the rigging. The runner plank, 16, is rigidly attached at its middle at right-angles.

to the backbone, 15, and is such as is customary in ice-boats, and is provided at each of its ends with a runner, 17, of the form and manner of attachment to the runner plank in common use. i

The tiller-post, 18, is attached to the back-bone, 15, passing through the baekbone and held in place by such means as y will permit the turning of the tiller post on its axis, a suitable tiller, wheel or other means being provided for turning the tiller post. The tiller post, 18, has rigidly attached to it on the under side of the backbone, 15, a sprocket wheel, 22, the tillerpost being extended downward to allow of such attachment, the sprocket wheel, 22, turning with the tiller-post, 18.

The shifting'member, 19, is a plank of tending aft thereof, the shifting mem ber, 19, being supported in its position under the back-bone, 15, by resting or hearing on the upper surface of the sprocket wheel, 22, attached to the tillerpost before mentioned. To prevent the forward end of the shifting member from tilting downward, abracket, 23, passing under the shifting member and attached to the sides of the cock-pit, 21, is provided, the bracket, 23, also limiting the distance of the lateral swing of the shifting member at its forward end. The shifting member, 19, may be provided at its forward end with a ballast weight.- 24, the weight being so attached to the shifting member as not to interfere with its passage from side to side under the back-bone, 15, its purpose being to afford additional stability to my ice-boat.

The rudder-rmmer, 20, is of the form commonly used in ice-boats and is attached to a post, 25, by means of cars and a pin or such means as will cause the rudder-runner to turn radially. in response to the turning of the post, 25, and also afi'ord the rudder runner a rocker movement in riding over rough or hummocky spots of ice. The post,

25, extends upward passing through the after end of the shifting member, 19, and held in place in the shifting member by any suitable means that will permit the post, 25, to turn on its axis. A sprocket-wheel, 26, is rigidly attached to the post, 25, between the rudder'runner, 20, and the under side of the shifting member, 19, so as to turn with the post, 25. A sprocket-chain, 27, en-

gaging the sprocket-Wheel, 22, on the tillerpost, 18, and also engaging the sprocket wheel, 26, connects the sprocket-wheels, 18 and 26, and causes correspondent movement of the rudder-runner, 20, to right or left as the tiller on the tiller-post, 18, is moved to right or left. Any desired movement of the rudder-runner at'an angle relative to the movement at any angle of the tiller on the tiller-post may be obtained by arranging the relative diameters of the sprocketwheels accordingly. But I do not restrict myself to the use of sprocketwvheels and chain, as I can use any means that will efi'ect correspondent movement of the tillerpost, 18, and the rudder-runner, 20, such as drums and a cable or a shaft and beveled gears.

The. lines of support of an ice-boat arethe lines forming the isosceles triangle from the point of contact of each runner, 17, with the ice to the point of contact of the rudder runner, 20, with the ice, an ice-boat when standing still or sailing in a light Wind thus having two lines of support, or three points of contact with the ice, Figs. 7 and 8, but,

having only one line of support, of two points of contact with the ice, in a wind strong enough to lift the windward runner off the ice, that is, the line from the point of contact of the lee runner with the ice to the point of contact of the rudder-runner with the ice, which line also becomes the line of stress. Then the windward runner lifts from the ice through wind pressure, the isosceles triangle which may be termed a. triangle of ice-contact support, becomes an isosceles triangle of part weight support and. part ice-contact support, that is, the weight of the boat and load, the word load here meaning the weight of the crew of the ice-boat, contained within this triangle forming the weight support, and the line of contact between the lee runner and the rudder-runner forming the line of icecon-taot support. If means be provided by which the rudder runner is shifted to leeward so that the lines of support become a scalene triangle instead of an isosceles triangle the effect of the weight support in holding the boat'down and preventing capsize becomes much greater, due to the longer are of leverage through which the eenters of gravity must belifted before reaching the point of capsize, the effect being that substantially all the weight of boat and load is utilized as ballast, the ballast weight, 24, also contributing to this result. In Figs, 7 and 8, in which my ice-boat and one of the usual type are shown, my ice-boat representing a boat of twenty-four foot back-bone, and the old form of boat one of thirty foot backbone, the dotted lines show the length of the lines of leverage of the respective boats to the lines of ice-support, and the portions 35 than the after end, but I do not restrict myof circles adjacent to each boat indicate the 'arcs'through which the respective boats must lift the centers of gravity before reaching the perpendicular or point of capsize. It will thus be seen that a shorter backbone and runner-plank canbe used, for example a t 24 foot back-bone and a 12 foot runnert plank in my construction being equal to a I foot back-bone and a 16 foot runner-l plank of the usual construction. This shift- I ing of the lines of support of an ice boat from an isosceles triangle to a sealene triangle, I attain by means of a shifting member, with a riuld'er-runner attached thereto. and this device and the principle therein in- "olved I claim as ne and original in the construction of a sail propelled ice-boat. lVhile the shifting'member primarily is intended to incr ase the stability of the no t boat, it. may be used to lessen the stability when desired. Thus in sailing in a light wind, the riuilder-runner. .20, may be shifted to windward instead of to leeward, and the crew moi'ed to.tbe lee side. of the cock-pit and the ballast weight, 24, also shifting to leeward. the object being to lift the windupon two lines of support or three points of contact with the ice, thus reducing friction and acquiring greater speed in a light wind.

The cock-Int, 21. is [n'cterably circular at each of its ends, the I'm-ward end l'ieing wider self to any particular form of cock-pit. 'lhe mate,

cock-pit 21, is placed well forward relative to the back-bone, 15, the object being to] bring the centers of gravity of the boat and the boat and load together or approxithe word load meaning the weight confined within the limits of the cot k- 'iit, thatis, the weight of the crew. By placing the cock-pit, 21, forward. I have found the center of gravity of my boat falls substantially on the point, 65. the center of gravity of the boat and load substantially on the point, 70, and the center of gravity of the load substantially on the point, 75, Fig. T, so that the weight bears more'directl v on the runner-plank and runners, the momen tum being absorbed as thrust. on the lee runner, when changing the course as"be't'ore stated, instead of in the. caseof the common type of ice-boat having, the cock-pit on the after end of the backbone in which case I have found these centers ofgravity to fall substantially on the points 80. 85, and 90, Fig. 8, the. momentum becoming drag on 1 the riulder-runnen I The cockpit, 21, may be attached along the sides of the back-hone,

its botton'retgtending below the lower line of the backbone, or ontop of the back-bone, or attached inanymanner t0 the back-bone I ward runner oti' the ice so that the boat sails I that will not interfere with the action of the shifting member, 19, and its attachments. But Ido not. restrict myself to a cockpit. placed forward, as the usual typeof cockpit placed aft may he used on my ice-boat, but in such case. the weight support of the load is not so etleetive in maintaining the stability of the ice-boat as where it is placed forward.

If the main-sheetof the mainsail be attached to the extreme after end. of the shifting member, 1:), this end of the shifting member and the rlulder-runner attached to it will shift to leeward automatically in re sponse to the pull of the mainsail to leearil when the boat is put. about, and remain in a leeward position because o'fthe continuous strain of the niainsail to leeward; But as it is desirable that the shifting mem= ber, 19, should be under the control of the crew or helmsnian, l. provide such means by cutting a box, 28, longitudinally in the back bone, 15, or the box, 28, may be made by building up that portion of the. back-bone, 15, iirbox form, provided suiiicient stiffness ofthe hack-bone is secured, ,Within the box, 28,- a slideway, 29, having a groove, 30, is arranged, which slideway may be made of hard wood or metal as preferred, upon which a wheeled carriage operates, to the ends of which cables fastened to either side of the shifting member, 19, are attached.- The wheeled carriage comprises two'sets of pairwheels, a forward set, 31, and an after set. 32, which travel on the slideway, 29, these wheels turning on shafts supported atthe ends of a double are, 33. A fore shearewheel, is placed between the forward pair wheels, 31, and an after sheavewheel, 55, is placed between the after pair wheels, 32, turning on the same shaft as the respective pair wheels. A fore cable, 36, is attached by suitztblenimns to the right hand. side of the shifting-member, 19, passing thence up and around a right hand pulleywheel, 37. on the bracket, 23, thence through the cockpit: to and around a. pulley-wheel,

and around apulley wheel, -13, from for-f V ward aft, thence to the under side of a pul ley wheel, 44, in the after end of the box,

thence over and forward tolbe under side of the aft sheave wheel, and thence over and aft toFa point- 45, on the 'righthand side of the box where made fast. An

operating lever, 46, pivoted at its bottom in a recess in the back-bone, 15, and extending upward between the two portions of the double are, 33, is arranged by engagement with pins on the inner sides of the are, 33, to draw forward or pull aft the carriage and thus through the action of the cables at tached to the carriage and to the shifting member to move the shifting member in the direction and to the extent desired by the operator and with it the rudder-runner. A suitable covering board with opening for the operating lever, 16, is placed over the box of the back-bone, 15. But I do not' restrict myself to the above described carriage and cables to shift the member, 19, as I can use any means which will give the de sired pivotal movement to the shifting member and be convenient and controllable by the crew or helmsman.

The modification of my ice-boat, Fig. 9, is in-its main features constructedsimilar to my ice-boat hereinbefore described, except that instead of a shifting member of the form, 19, the back-bone, 15, is cut into two portions, 'the forward portion, 47 being rigid with the runner-plank and the aft portion, 48, hinged to the forward portion at a oint in the back-bone, 15, substantially where the tiller-post, 18, passes, through the back-bone, 15, and the shifting member, 19,

is pivoted in my ice-boat first herein de-' scribed, the intention being that the rudderrunner, 20, should be attached to this hinged portion, -18, which having the ability to swing to right or left of the line of the rigid part, 47, of the back-bone, 15, thus takes the place of the shifting-member 19.

The construction also diti'crs from my first described boat in that the cock-pit, 21, is fixedly attached to the upper side of the hinged part. 48, ot the back-bone and swings therewith, the forward end of the cock-pit being arranged to pass over or clear the upper side of the rigid portion, 47, of the back bone in swinging from side to side. ,1 bracket, 2?), similar to the bracket of my first described boat, fastened to each side of the cock-pit and passing under the rigid portion, 47, of theback-bone is provided to hold the coclepit down on the rigid back-bone and to limit the lateral swing of the cockpit at its forward end. S])l()('l(0l"\\'ll((3l5 and chain can be used to connect the tiller-post and the post of the riuldcr-runner, to provide correspondent movement of the tiller post and the rudder-runner as in the case of my first described boat. \Vhen it is borne in mind that in sailing an ice-boat the heln'is man and crew lie down in the cock-pit tacing forward, with the tiller extending over the shoulder of the helmsman, the effect of this arrangement of cock-pit. is that the weight of the helmsman or crew is shifted to Windward of the line of the rigid backbone and affords a long line of ballast leverage and actually provides shifting ballast for an ice-boat. Instead of the cable and carriage means hereinbefore described, cables 49 and 50, and pulley wheels'51 and 52 means of shifting with the purchase on the rigid portion ofthe back-bone and attachment to the forward sides of the cock-pit may be used to move thevhinged portion of the back-bone to right or left as desired. Instead of at taching the cock-pit to a hinged portion of the'back-bone, the floor of the cock-pit can be made of sutticientstrength and the cock pit itself pivoted on the rigid part of the backbone by means of the tiller-post'passing through the floor and the post of the rudder-runner can be extended up through the rear end of the cock-pit, thus making the cock-pit itself in effect a shifting member for the rudder-runner, and such construction I claim as my invention.

In the modification of my ice-boat, Figs. 10 and '11, I provide a shifting means comprising a supporting member, 53, rigidly attached at its middle to the under side of the extreme after end of the back-bone, 15, at right angles thereto, and having a rudderrunner pivoted at the middle of the supporting member in the line of the back-bone, the post of this riulder-runner extending upward through the back-bone, and a rudderrunner pivoted at each end of the supporting member equi-distance from the middle rudder-runner, that is, a shifting means provided with three rudder-runners. The rudder-runners are in form and means of attachment, to the supporting member, 53, similar to the rudder-runner, 20, firstdescribed herein, butthe bottom or shoe of the middle riulder-runner is extended downward to a lower plane than the plane of the bottoms or shoes of the side rudder-runners, Fig. 12, the intention being that when the ice-boat is standing still or sailing in a light wind the middle rudder-rimn'er only will be in contactwith the ice and the lines of support will form an isosceles triangle, but when the boat lifts under wind pressure the niiiidle riuldcr-runncr will'leave the ice and the o tside lee rmldcr-runner will come into, contact with the ice, thus automatically shifting the lines of support to ,a scalene triangle, the load aifording long ballast leverage and great stability, and an ice-boat adapted to use for pleasure sailing. by a woman or child. Means of steering and control is bad by the use of the sprocket wheels and the sprocket-chain device before described operating on the tiller-post and the post of the middle rudder-rminer. To

the" right-hand outer rudder-runner, a similar shaft, 55, to the middle rudder-runner and a similar shaft, 56, to the left-hand outer rudder-runner, these shafts, being connected at their forward ends by link bars, 57. If

the cock-pit is placed farther aft on the backbone the sprocket-wheels and chain may de discarded and a tiller used, formed by the extension forward of the shaft, 55, or by attaching a tiller to the forwardencl of the shaft, 55. i

In the niodilication'of my ice-boat shown in Fig; 14, another form of shifting means therefor is used, comprising an inverted V- shaped or forked extension of two diverg- 111g planks with the point or apex forward fixedly attached to the rear end of the backbone, 15, a middle,rudder-runner, 59, being attached to and turning with a tiller-- post extending upward through the backbone'and'the cock-pit at the forward point of the V-Lshaped extension vand an outer rudder-runner, GO and'6l, pivoted at each of the rear ends of the V-shaped extension.

As in the case of my last described boat, the

forward or'middle riulder-runner, 59, extends downward tea-lower plane than the plane of theouter rudder-runners, 60 and 61, the intention being that when the ice boat is standing still or sailing in a light wind the middle rudder-runner, 59, only will'be in contact with the ice and the lines of support will form an isosceles triangle, but when the boat llfts under wind pressure the middle rudder-runner will leave the ice and the lee rudder-runner, 60 or 61, as the case may be, will come in contact withthe ice, thus automatically shifting the lines of support to a scalene triangle. A boat of this construction has great stability and can carry a large sa il area With resultant great speed, due to the" long line 'of leverage through which the centers of gravity must be-lifted before the boat capsizes. This con" struction provides particularly convenient means of entrance to the cock-pit, that is over the aft or rear end thereof, clear of all attachments. Correspondent movement of the middle rudder-runner, 59, and the side rudder-runners, 60 and 61,- is had by means of a double-sprocketwheel, G2, rigidly attached to the tiller-post, 63, which is also the postof the middle rudder-runner, 59, and turning therewith, and a singlesprocket-wheel, 6i, attached'to the post of each of the side rudder-runners, 60 and 61,

' and turning therewith, connection between the double sprocket-Wheel, 62, and the single sprocket-Wheel, 64, being had by means of a sprocket-chain for each of said sprocketwheels, 64. But I do not restrict myself to' the sprocket-Wheel andchain arrangement, as drums and cable'scan be used, or shafts and bevel gears, or-shafts and link bars, subsails, as either'jib and maiusail, latteen, or

mainsail only, or cat-rig, maybe used, provided the arrangement of the sails is such as to afford proper sail balance.

'stantially similar in arrangement to those d5 hereinbefore described, canbe used.

As the sail. propelling means my ice-boats are not restricted to any particular rig of Having fully described my invention what I claim and desire to protect by, Letters Patent 1s:

l. A sail. propelled ice-boat OOIUI'HlSlIlg,

with means of attachment for the several parts, a backbone, a runner-plank, runners providing forward support, a rudder-ruimer in the line of the backbone providing aft,

support when the boat is on a horizontal plane, means for shifting the aft support to right or left of the line of thebackbonc,

thereby shifting the lines of support,o'tbthe ice-boat from an isosceles triangle to a Scalene triangle, a, cock-pit, and means of steering and control; siibstantlally Sel'[ forth.

2. A sailpropelled ice-boat comprising,

with means of attachment for the several parts, a backbone, a'riinner' plank, runners providing forward support, a cock-pit rigid in theline of the back-bone, a rudder-r mncr in the li'nc ,of the back-bone providing aft support when the boat 15 on ahor1zontal plane, a shifting member attached to the back-brme and extending forward and aft in the line thereof and adapted tov shift the aft support to right or left of the'line of the back-bone thereby shifting the lines of support of the ice-boat from an isosceles-triangle to a scalene triangle, and means of "steer,

' ing and control; substantially as set forth.

3. A sail propelled ice-boat comprising a backbone, a runner-plank attached to the.

back-bone, a runner attached to each end of l the runner-plank, a cock plt attached to the f backbone, a runner attached to each end of the runner-plank, a cock-pit attached to-the back-bone and rigid in the line thereof, a shifting member attached to the backbone on the under side thereof and extending for- Ward and aft of the point of its attachment to the back-bone, means operating the shifting member and controlling the direction and distance of the shift thereof, a rudderrunner attached to the after end of the shifting member and shifting therewith, a tillerpost attached to the back-bone, means connecting the tiller-post and the rudder-runner and providing correspondent movement of the tiller-post and the rudder-runner, and means controlling said correspondent movement; substantially as set forth.

5. A sail propelled iceboat comprising a back-bone, a runner-plank attached to the backbone, a runner attached to each end of the runner-plank, a cock-pit attached to the back-bone and rigid in the line thereof wherein the centers of gravity of the boat and of the boat and load approximate, a shifting member attached to the back-bone on the under side thereof and extending forward and-aft of the point of its attachment to the back-bone, a ballast weight attached to the forward end of the shifting member, means operating the shifting member and controlling the direction and distance of the shift thereof, a rudder-runner attached to the after endof the shifting member and shifting therewith, a tiller-post attached to the back-bone, means connecting the tiller-post and the rudder runner and providing correspondent movement of the tiller-post and the rudder-run ner, and means controlling said correspondent movement; substantially as set forth.

6. In an ice-boat of the character described having a back-bone and means of forward support, the combination of a rudder-runner in the line of the back-bone providing aft support when the boat is on a horizontal plane, and means for shifting the aft support to right or left of the line of the back-bone thereby shifting the lines of support of the ice-boat from an isosceles triangle to a scalene triangle; substantially as set forth.

7. In an ice-boat of the character described having means of forward support, the combination of a back-bone, a shifting member attached to the back-bone on the under side thereof and extending forward and aft of the point of its attachment to the baclc bone, and a rudder-runner attached to the after end of the shifting member and shifting therewith; substantially as set forth.

8. In an ice-boat of the character described having means of forward support, the combination of a back-bone, a shifting member attached to the back-bone on the under side thereof and extending forward and aft of the point of its attachment to the backbone, a rudder-runner attached to the after end of the shifting member and shifting therewith, and means operating the shifting member and controlling the direction and distance of the shift thereof; substantially as set forth.

9. In an ice-boat of the character described having means of forward support, the combination of a back-bone, a shifting member attached to the back-bone on the under side thereof and extending forward and aft of the point of its attachment to the backbone, a ballast weight attached to the forward end of the shifting member, and a rudder-runner attached to the after end of the shifting member and shifting therewith; substantially as set forth.

10. In anice-boat of the character described having a back-bone and means providing forward support and means providing aft support in the line of the back-bone when the boat is on a horizontal plane, a means for shifting the aft support to right 'or left of the line of the back-bone thereby 

